Nebraska Lieutenant Governor Rick Sheehy, a prime candidate in the race to succeed current Governor Dave Heineman, resigned suddenly on Saturday due to a scandal involving the use of his state-issued cell phone.

Reuters:

The Omaha World-Herald investigation found that the 53-year-old Republican made about 2,000 late-night calls to four women, other than his wife, on his state-issued cell phone over four years. The newspaper plans to publish results of the investigation on Sunday.

Colleen Sheehy, his wife of 28 years, filed for divorce in July 2012, according to the newspaper.

Governor Dave Heineman announced the resignation of Sheehy, a rising star in state politics, at a news conference. The governor said he was "deeply disappointed" and that Sheehy had done good work, but "trust was broken."

"Public officials are rightly held to a higher standard," Heineman said at the news conference, provided on the Omaha World-Herald website.

Heineman will leave office in 2015 and Sheehy had announced that he would run for governor. He was considered a leading candidate. Heineman selected Sheehy as lieutenant governor in 2005 after moving into the governor's office to replace Mike Johanns, who was tapped as U.S. agriculture secretary.

Heineman and Sheehy were elected to their first full term in 2006 and re-elected to a second term in 2010.

There is probably more to this story. Sheehy's wife filed for divorce last July. It seems likely there was more going on than late night calls to his girlfriends.

Nebraska is a generally reliable Republican state. Democrats who run statewide are far more conservative than their Washington counterparts, but so far, there is no credible Democrat who has announced plans to run. AP reports several possible Republicans including Attorney Genearl John Bruning.